Elucidation of the Microbial Community in Activated Sludge Using PCR-DGGE Analysis in Arid and Semi Arid Regions of Rajasthan

Activated sludge is the most commonly used process to treat sewage and industrial waste waterby micro organisms. The activated sludge system depends on the activities of microbial communitiespresent in the sludge. However, exact knowledge of the microbial community structure in waste watertreatment plants is limited. In this study, the bacterial diversity of activated sludge was investigated inthe two waste water treatment plants by using denaturing gradient gel electrophoresis (DGGE) of PCRamplified16S ribosomal DNA fragments. Dominant bands from DGGE profiles were excised andsubjected to sequencing to identify the dominant genotypes. Sequence analysis gave insights into theidentities of the predominant bacterial populations present. The DNA sequencing results indicated themicrobial diversity, revealing that the dominant bacteria present in Bramhapuri waste water treatmentplant is Acinetobacter sp. whereas the dominant bacteria in Pratapnagar (Delawas) waste watertreatment plant is Alpha-proteobacteria. Futhermore, cluster analysis of the DGGE profiles indicatedsignificant diversity in the bacterial community by depicting two distinct clusters for each waste watertreatment plant. These data endorse the ability of PCR-DGGE method to identify and characterizebacterial community from activated sludge.